One indicator of the state of health of a lead-acid battery is the conductance of the battery. Conductance can be defined as the AC resistance ideally measured at different frequencies. The measured conductance is linearly related to the Cold Cranking Amp (CCA) for the battery and thus can be used to provide an indication of the state of health of the battery.
Unfortunately, conductance of a battery cannot be easily obtained. Measuring conductance to assess the state of health of a battery requires an undesirable addition of hardware and firmware. As a result, the measurement of conductance to assess the state of a battery is infrequently used.